An Optical Line Terminal (OLT) is a terminal device for connecting to an optical fiber trunk, which can achieve functions of controlling and managing Customer Premises Equipment, i.e., Optical Network Unit (ONU). The ONU is an optical access network device which is generally used in a corridor or at a home in Integrated Terminal Management System (ITMS).
TR069 (DSL Forum CPE WAN Management Protocol) is one of the technical specifications developed by the DSL (Digital Subscriber Line) forum and is entitled CPE (Customer Premises Equipment) WAN (Wide Area Network) Management Protocol. It provides a general framework and protocol for managing and configuring home network devices in the next generation network so as to provide, at a network side, a remote centralized management on the devices in a home network including a gateway, a router, a set top box and the like.
Wide Area Network (WAN) connection refers to a way of connecting a device to a WAN. For example, a home gateway is generally connected to the outside via an Asymmetrical Digital Subscriber Loop (ADSL), a Local Area Network (LAN), the Ethernet or an Ethernet Passive Optical Network (EPON)/Gigabit Passive Optical Network (GPON). In this case, it is defined that the WAN connection of the home gateway is the ADSL, the Ethernet or the EPON/GPON.
E8 is a home gateway provided by China Telecom, and E8C is a C-type home gateway provided by China Telecom. Home gateways of China Telecom are managed using the TR069 protocol. Fiber-to-the-x (FTTx) refers to fiber access, wherein x refers to an access point. Fiber-to-the-Building (FTTB) refers to the extension of fiber to a building, and Fiber-to-the-Home (FTTH) refers to the extension of fiber to a home.
The main problems which FTTH faces are as follows: 1, the connection to home is difficult to realize as it is difficult to deploy optical fibers; 2, the problem of the shortage of construction fund is prominent because of the high cost of FTTH; and 3, the secondary splitting of optical fibers also increases the construction cost of FTTH. FTTB faces such problems that non-operators are in a passive position in FTTB popularization, the installation rate of FTTB cannot be checked conveniently and the supply of power is not guaranteed fully.
To address the problems currently existing in FTTH and FTTB, a new optical fiber access solution is provided which is called enhanced FTTH. In this solution, a card insertion scheme is used. Referring to FIG. 1, an ONU is made into a sub-card and each sub-card is an independent ONU. The ONU is inserted into a machine frame that can be flexibly positioned in a corridor or at a gate. With the existing cables (network lines or telephone lines) for the connection to a home, each card can flexibly provide an access mode to support a broadband access and a voice service without changing the current installation flow of FTTH, thereby guaranteeing the supply of power and minimizing the construction cost. The enhanced FTTH device shown in FIG. 1 is implemented as follows: an independent Central Processing Unit (CPU) and an independent Passive Optical Network Media Access Control (PONMAC) module are provided on each sub-card, that is, each interface card is provided with the circuit of a standard ONU, and all sub-cards share one optical module. Referring to FIG. 1 in detail, a downlink data stream is sent to each PONMAC via a Field Programmable Gate Array (FPGA), the PONMAC finds its own data by filtering. In the uplink direction, only one PONMAC can send data at a time, which is realized by the FPGA using a high-speed switch. When a certain ONU needs to send data, the ONU connects its PONMAC to the high-speed switch. As such, each ONU is unaware of the existence of the other ONUs. The implementation scheme shown in FIG. 1 is relatively simple in terms of software implementation because of no need for changing existing ONU software. The following problems, however, exist.
(1) It has high hardware cost. Each ONU is configured with a CPU and a PONMAC. In particular, a FPGA is introduced for sharing an optical module, which leads to a sharp increase in cost as the number of the sub-cards increases.
(2) The FPGA cannot switch among the ONUs rapidly as the uplink interface rate increases, resulting in a bottleneck in the uplink interface rate. Therefore, it is impossible to introduce an uplink interface with a higher speed.